Capacitive touch sensor and method

Patent metadata

Field	Value
Publication number	US-11233508-B2
Application number	US-202016735878-A
Country	US
Kind code	B2
Filing date	Jan 7, 2020
Priority date	May 6, 2014
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A capacitive touch sensor is disclosed for use with input signal. The capacitive touch sensor includes a number n of input/output lines. Each of the number n of input/output lines is electrically disconnected from every other of the number n of input/output lines. Each of the number n of input/output lines is arranged to cross every other of the number n of input/output lines. Each of a number β of positions includes one of the number n of input/output lines crossing another of the number n of input/output lines.

First claim

What is claimed is:

1. A method comprising:
receiving a preliminary fault indication associated with one of a plurality of button areas in a capacitive touch sensor, wherein each of the button areas is associated with a respective set of two pins of a plurality of pins;
in response to receiving the preliminary fault indication, clearing the preliminary fault indication;
in response to clearing the preliminary fault indication, scanning the plurality of button areas in the capacitive touch sensor to obtain a respective parameter value for each of the plurality of button areas, wherein the scanning includes:
for each respective pin of the plurality of pins, outputting a transmit signal on the respective pin and scanning at least one other pin of the plurality of pins for a respective one or more received signals; and
determining the respective parameter value for each of the plurality of button areas based on the respective one or more received signals;

comparing each obtained parameter value to each of a plurality of fault values;
determining whether at least one of the obtained parameter values matches any one of the plurality of fault values; and
responsive to determining that at least one of the obtained parameter values matches any one of the plurality of fault values, indicating to the processor coupled to the capacitive touch sensor the detection of a fault in the capacitive touch sensor.

2. The method of claim 1 , wherein indicating to the processor coupled to the capacitive touch sensor the detection of a fault includes:
asserting a fault interrupt; and
providing a fault code corresponding to the detected fault.

3. The method of claim 1 , wherein the plurality of fault values is stored in a fault table that is stored in a memory coupled to the processor.

4. The method of claim 1 , wherein the capacitive touch sensor includes:
n input/output lines, wherein n>2, and wherein each of the n input/output lines is arranged so that it is electrically disconnected from each other one of the n input/output lines and while crossing each other one of the n input/output lines; and
β positions, wherein each of the β positions corresponds to a respective button area at which one of the n input/output lines crosses another one of the n input/output lines; and
wherein the scanning includes sequentially applying a signal to each one of the n input/output lines.

5. The method of claim 4 , wherein β is an integer having a value determined as β=Σ 1 (n-1) x.

6. The method of claim 1 , wherein the respective parameter value for each of the button areas includes one of voltage, current, capacitance, inductance, resistance, impedance, change in voltage, change in current, change in capacitance, change in inductance, change in resistance, change in impedance, or any combination thereof.

7. The method of claim 1 , wherein the respective parameter value for each of the button areas is a capacitance.

8. A method comprising:
performing a first scan on a plurality of button areas in a capacitive touch sensor to obtain a respective parameter value for each of the plurality of button areas;
comparing each obtained parameter value from the first scan to each of a plurality of fault values;
determining whether at least one of the obtained parameter values from the first scan matches any one of the plurality of fault values; and
when at least one matches any one of the plurality of fault values, performing a second scan on the plurality of button areas in the capacitive touch sensor to obtain a respective parameter value for each of the plurality of button areas;
comparing the obtained parameter values from the second scan to the obtained parameter values from the first scan;
determining whether the obtained parameter values from the second scan match the obtained parameters from the first scan;
responsive to determining that the obtained parameter values from the second scan match the obtained parameters from the first scan, indicating to a processor coupled to the capacitive touch sensor the detection of a fault in the capacitive touch sensor.

9. The method of claim 8 , wherein indicating to the processor coupled to the capacitive touch sensor the detection of a fault includes:
asserting a fault interrupt; and
providing a fault code corresponding to detected fault.

10. The method of claim 8 , wherein the plurality of fault values is stored in a fault table that is stored in a memory coupled to the processor.

11. The method of claim 8 , wherein the capacitive touch sensor includes:
n input/output lines, wherein n>2, and wherein each of the n input/output lines is arranged so that it is electrically disconnected from each other one of the n input/output lines and while crossing each other one of the n input/output lines; and
β positions, wherein each of the β positions corresponds to a respective button area at which one of the n input/output lines crosses another one of the n input/output lines; and
wherein the scanning includes sequentially applying a signal to each one of the n input/output lines.

12. The method of claim 11 , wherein β is an integer having a value determined as β=Σ 1 (n-1) x.

13. The method of claim 8 , wherein the respective parameter value for each of the button areas includes one of voltage, current, capacitance, inductance, resistance, impedance, change in voltage, change in current, change in capacitance, change in inductance, change in resistance, change in impedance, or any combination thereof.

14. The method of claim 8 , wherein the respective parameter value for each of the button areas is a capacitance.

Assignees

• Texas Instruments Inc

Inventors

• Jun Zhang
• Ge Shen
• Cheng xu kang
• Yi Zhou
• Meng Hao
• Jun Ji Ru

Classifications

• H03K17/9622 Primary

  using a plurality of detectors, e.g. keyboard · CPC title

• H03K2217/96066

  Thumbwheel, potentiometer, scrollbar or slider simulation by touch switch · CPC title

• H03K2017/9613

  using two electrodes per touch switch · CPC title